1. Field of the Invention
This invention relates to an ink composition and a recording method, particularly to an ink composition which shows excellent water resistance on plain paper, and a recording method.
2. Description of the Related Art
In recent years, with the popularization of computers, ink jet printers are broadly used, not only at offices but also at homes, for the purpose of printing letters and pictures on paper, films, cloth and the like.
The ink jet recording method includes a system in which droplets are discharged by applying pressure using a piezo element, a system in which droplets are discharged by generating bubbles in the ink with heat, a system in which ultrasonic wave is used, and a system in which droplets are sucked and discharged by electrostatic force. As the ink for these ink jet recording system, water-color ink, oil base ink or solid (melt type) ink is used.
Among these inks, water-color ink is relatively superior to oil base ink and solid (melt type) ink, in terms of the possibility of taking a triangular position regarding its production, handling, odor, safety and the like, so that it is now the main stream of the ink for ink jet recording use.
For the dyes to be used in these inks for ink jet recording use, there are requirements such as high solubility in solvent (ink medium), ability to perform high density recording, proper hue, excellent solidity for light, heat, air, water and drugs, good fixing ability to and difficulty in soaking into image receiving material, excellent shelf life as ink, no toxicity, high purity and inexpensive availability. However, it is extremely difficult to find a dye which satisfies the aforementioned various requirements at a high level. Particularly, the excellent hue and the solidity conflict in most cases, for example, it is difficult to obtain a coloring material for magenta ink use which satisfies the aforementioned various requirements, and it is particularly difficult to find a dye that has both of good magenta hue and light solidity capable of standing against oxidizing atmosphere.
Thus, though various dyes and pigments have already been proposed as compounds for ink jet use and are now actuary used, it is the present situation that a dye which satisfies all of the aforementioned requirements has not been found yet.
In the case of the conventionally well known dyes and pigments to which color index (C.I.) numbers are given, it is difficult to simultaneously obtain both of the hue and solidity required for the ink for ink jet recording use.
In order to solve such a problem, a magenta dye having excellent weather resistance in JP-A-2002-371079 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) and an ink for ink jet use in JP-A-2002-371214 have been proposed.
However, the aforementioned dyes or inks have a problem in that their water resistance on plain paper is insufficient.